Nitrendipine is a drug belonging to the general class of compounds known as dihydropyridine calcium channel blockers. This class of drugs has the property of inhibiting the transmembrane influx of calcium ions into cardiac muscle and smooth muscle without changing serum calcium concentrations. The contractile processes of cardiac muscle and vascular smooth muscle are dependent upon the movement of extracellular calcium ions into these cells through specific ion channels. Nitrendipine relaxes coronary vascular smooth muscle, and exerts its hypotensive effect at drug levels which cause little or no weakening of cardiac contractions.
Nitrendipine is presently administered as a racemic mixture. That is, it is a mixture of optical isomers, called enantiomers. Enantiomers are structurally identical compounds which differ only in that one isomer is a mirror image of the other and the mirror images cannot be superimposed. This phenomenon is known as chirality. Most biological molecules exist as enantiomers and exhibit chirality. Although structurally identical, enantiomers can have profoundly different effects in biological systems: one enantiomer may have a specific biological activity while the other enantiomer has no biological activity at all, or may have an entirely different form of biological activity.